Progerterone levels in England

Well I had a MMC last year and became paranoid that it may have been due to low progesterone. I got my GP to test for this and at 7DPO it came back at 58.6. I also had one done 6 days before at 1DPO and it was 11 do it had obviously gone up quite a lot. I turned out to be PG and am now nearly 5 weeks on sunday.

When I asked my dr if that was a good level - he said it was OK but nothing to shout about !!! What on earth is that supposed to mean. Does anyone have a chart with the UK levels on or know what it shoud be in early PG ?